Continuously variable frequency swinging armature motor and drive

ABSTRACT

Disclosed herein is a power device. The power device has a power source; timing circuitry powered by the power source for producing a current pulse output having a pulse width; a switch for triggering the current pulse output produced by the timing circuitry; an armature motor powered by the power source and in electrical communication with the timing circuitry for receiving the current pulse therefrom, the armature motor comprising: an electro-magnetic core; a first winding for carrying electric current to energize a magnetic field associated with the electro-magnetic core; a second winding for carrying current to reset the magnetic field associated with the electro-magnetic core, the first and second windings wound about the electro-magnetic core; and a swinging armature for providing movement in response to the energizing of the magnetic field about electro-magnetic core. The first winding and the second winding are bifilar wound together about the electro-magnetic core. When the switch triggers the current pulse from the timing circuitry, the armature operates at the current pulse output pulse width. The invention permits higher frequency operation and more output pressure/output to be generated with devices with variable speed motors.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.11/276,412, filed Feb. 28, 2006, now U.S. Pat. No. 7,298,101 which alsoclaims the benefit of U.S. Provisional Application Ser. No. 60/657,231,filed on Feb. 28, 2005, the teachings and disclosures of which areherein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to electromagnetic motors and theircontrol circuitry for power tools and devices, and more particularly, toa continuously variable frequency swinging armature motor and drive forimproving the performance of such power tools and devices.

2. Description of Related Art

In the design of power tools and other work devices and machines, it isa continuing design goal to improve performance parameters to enhanceuser operation and productivity. In such devices as airless paintsprayers, high pressure washers, electric caulk guns, speed staplers,low volume water or air pumps, portable high pressure air compressors,power chisels and scrapers, among others, such parameters may includeincreasing output volumes, increasing user adjustability of output,increasing operating frequency ranges, and reducing acoustic noise,heat, and weight.

The ability to improve these parameters, particularly the output volume(e.g., of a paint sprayer), without increasing the size and power of themotors and pumps within such devices would be highly advantageous.

In devices using electromagnetic-based swinging armature motors, it hasbeen found that the electromagnets that use single windings can bedesigned to improve performance of the devices. Such devices that use asingle winding are usually powered directly from an alternating current(“AC”) line. This allows the armature to close at twice the linefrequency, i.e., one time for the positive one-half of the AC waveformand one time for the negative one-half of the AC waveform. For a 60 Hzline, for example, the armature will move, open, and close 120 times persecond with such an arrangement. Control over output volume (or otherwork done) is commonly accomplished by limiting how far the armature canmove. This is sometime done by an adjustable mechanical stop. In otherwords, in order to control the output volume, you have to limit how farthe armature can move, which is commonly accomplished by providing anadjustable mechanical stop. It would be preferable to electronicallyadjust the output, not mechanically.

Using a sine wave voltage to power the electromagnet is generallyinefficient because the waveform has to fall to near zero volts beforethe armature can start to move to its open position. Therefore, there isless time for the pump's piston to fully open, and thus, there is lesstime for paint to enter into the pump section or reservoir of a typicalpaint sprayer. In addition, the armature also experiences a so-calledbounce when it hits its open position stop. The bounce increases thesettling time of the armature, thereby decreasing the overall outputvolume of the paint delivered from the typical paint sprayer. Therefore,it has been found that using other waveforms can improve electromagneticmotor performance. Also, where a DC signal is used to power anelectromagnetic-based swinging armature motor, there is a need to have acurrent signal with a pulse width and associated circuitry that willallow the magnetic field generated by the electromagnet to collapsequickly and store the resulting energy within the circuit.

Accordingly, there is a need in the industry for a variable frequencydriven swinging armature motor that can be continuously driven over awide range of frequencies. Previous frequency adjustment solutionsprovided a circuit to selectively skip cycles or half cycles of the ACwaveform. See e.g., U.S. Pat. Nos. 4,517,620 and 4,705,995 toHans-Joachim Boll, the disclosures of which are hereby incorporated byreference in their entirety. Typically, this was accomplished by using atriac-type device (e.g., two thyristors wired in series, but pointing inopposite directions) that turns on and off at the zero crossings.Because the minimum period that can be skipped is one-half of a 60 Hzcycle, the frequency can only be reduced in 30 Hz increments whilemaintaining steady symmetrical output pressure and flow in theassociated pump, which translates into drive frequencies of 120 Hz, 90Hz, 60 Hz, and 30 Hz. Such frequency control limitations are commonlyrecognized as shortcomings in the industry. Therefore, a continuouslyvariable frequency driven swinging armature motor would provide numerousbenefits to the industry. Such a motor would provide more versatilityand increase control in many applications. And for any applicationswhere the lowest desired frequency is higher than the normal AC linefrequency (i.e., 50-60 Hz), the electromagnet can be made physicallysmaller and still generate the same force, or alternatively, generatemore force with the same size of electromagnet.

In accordance with the foregoing, an electromagnet based motor andassociated circuitry incorporating improvements not heretofore employedfor use in power tools and devices would be highly desirable.

BRIEF SUMMARY OF THE INVENTION

A power device, comprising a power source; timing circuitry powered bysaid power source for producing a current pulse output having a pulsewidth; a switch for triggering said current pulse output from saidtiming circuitry; and an armature motor powered by said power source andin electrical communication with said timing circuitry for receivingsaid current pulse from said timing circuitry, said armature motorcomprising an electromagnetic core; a first winding for carryingelectrical current to energize a magnetic field associated with saidelectromagnetic core; a second winding for carrying electrical currentto re-set said magnetic field associated with said electromagnetic core,said first winding and said second winding bifilar wound about saidelectromagnetic core; and a swinging armature for providing movement inresponse to energizing said magnetic field associated with saidelectromagnetic core, wherein when said switch triggers said currentpulse from said timing circuitry, said armature operates at said currentpulse output pulse width.

BRIEF DESCRIPTION OF THE SEVERAL VIEW OF THE DRAWINGS

Many aspects of the invention will be better appreciated and understoodin conjunction with the following drawings and Detailed Description ofthe Invention, which form integral components of this Specification, inwhich like reference numerals generally represent like elements, and inwhich:

FIG. 1 is an electrical schematic of an electromagnet and associatedcircuitry in accordance with one aspect of the present invention; and

FIG. 2 is a side-elevation, partially in cross-section, of a hand-heldspray gun incorporating the control circuit of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, an electrical circuit 10 of a variablefrequency driver and control circuit for a swinging armature motor isshown 10. The circuit 10 includes a common power source 11 (such as120VAC) that provides the requisite input voltage for the applicationsand circuitry desired.

The circuit 10 is associated with a power device (e.g., see FIG. 2) toimprove the performance thereof, examples of which include, but are notlimited to, airless paint sprayers, high pressure washers, electriccaulk guns, speed staplers, low volume water or air pumps, portable highpressure air compressors, power chisels and scrappers, and the like.Many other types of applied technologies may also be used in the presentinvention, which is particularly well-suited for applications in whichadditional throughput (e.g., of air, paint, water, etc.) of the powerdevice is desired. Such devices commonly have pump pistons that aredriven by a coil/oscillating armature combination.

A preferred way to adjust throughput within a desired range of a givenpower device (e.g., in painting applications, from a fine mist to fulldroplets) may be accomplished with an adjustment mechanism VR1. Theadjustment mechanism VR1 is shown as a variable resistor orpotentiometer, but other suitable adjustment mechanisms VR1 may also beused. The adjustable mechanism VR1 permits continuous frequencyadjustment control within a given range, with the size of the adjustmentmechanism VR1 being selected to obtain the desired drive frequencywithin the desired frequency adjustment range. In a preferredembodiment, a frequency adjustment range of 25-150 Hz is selected,although other ranges are also possible.

A low level signal switch SW1 is in electrical communication with theadjustment mechanism VR1. When closed, the switch SW1 provides a signalpath to ground. In a preferred embodiment, the adjustable mechanism VR1and switch SW1 are electrically connected to the circuit 10 through anexternal mounting 12 that is not otherwise physically mounted to thecircuit 10. Alternatively, these components may also be integratedcomponents of the electrical circuit 10.

In any event, the adjustable mechanism VR1 and switch SW1 areelectrically connected to and associated with a timing module 14 of thecircuit 10. Although many timing circuit configurations may be used aspart of the timing module 14, one exemplary embodiment includes a pairof 7555 timing chips IC1 (7555 Clock) and IC2 (7555 One Shot), which areused to control the timing and duration of signal pulses to be usedwithin the circuit 10. In a preferred embodiment, both timing chips IC1and IC2 have the following pin assignments:

1 GND 2 Trig. 3 OUT 4 Reset 5 Cont. V 6 Tres. 7 Dis. 8 V+The various functionalities of the timing chips IC1 and IC2 arewell-known and will not be further described except as they are usedherein to produce the necessary signal pulse.

In any event, the timing module 14 of the circuit 10 preferably includesthe following components: resistors R1, R2, R3, and R4; timing chips IC1and IC2; and capacitors C3, C4, C5, C6, C7, and C9. As shown, resistorsR1 and R2 are electrically associated with IC1, as are capacitors C4,C5, and C9. Likewise, resistors R3 and R4 are electrically associatedwith IC2, as are capacitors C6 and C7. Capacitor C3 is electricallyassociated with both timing chips IC1 and IC2.

As an exemplary, representative, and non-limiting example, numericalvalues are set forth below for the electrical circuit 10 of FIG. 1. Theyare only provided to convey an understanding of the invention, and theyare not intended to restrict the scope of the invention in any way.Nevertheless, preferred circuit elements of the circuit 10 can bedimensioned as follows:

R1 2.2 kΩ R2 2.2 kΩ R3 100 kΩ R4 23.7 kΩ R5 47 kΩ R6 47 Ω R7 2.2 kΩ R822 Ω R9 22 Ω VR1 0-10 kΩ C1 390 uF C2 5.1 nF C3 3.3 nF C4 1 uF C5 0.01uF C6 0.01 uF C7 0.1 uF C8 100 uF C9 47 uF

As shown in FIG. 1, the switch SW1 triggers a low level signal on andoff by making one of its signal paths into an open circuit. As theadjustment mechanism VR1 is adjusted, its variable resistance, in serieswith a resistor R1, will produce a total resistance at pin 6 of IC1,thereby adjusting the clocking function thereof. The operation of IC1 isalso linked to IC2 since the output pin 3 of IC1 is connected to theinput trigger pin 2 of IC2. In operation, it is the output from outputpin 3 of IC2 that has the desired square wave on branch 16 with thedesired pulse width. In the configuration depicted, a pulse width ofabout 2.8 ms is preferred. However, the pulse width is optimizedaccording to a given electromagnet size. For example, if the size of theelectromagnet is changed, the desired pulse width would also need tochange in order to be optimized to the new electromagnet size. It isfurther contemplated that automatic adjustment of the pulse width basedon, for example, the slope of current in the electromagnet, or anothersuitable parameter, is possible to allow for fully automaticoptimization of the pulse width to accommodate fluids having varyingproperties, such as different fluid viscosities.

The signal on branch 16 is then transmitted to a switching network 18,which preferably includes the following: a common base/common emitterNPN-PNP transistor pair Q1, Q2; a switching device such as a MOSFET Q3;resistors R6, R7, R9; and a capacitor C2. The switching of the MOSFET Q3is tied into, and affects the operation of, an armature motor M1 incommunication therewith. The armature motor M1 is a swinging armaturemotor, and it includes an electromagnetic wound coil. The coil includesan electromagnetic core 22 and a first winding 24 for carrying electriccurrent to energize a magnetic field associated with the electromagneticcore 22. The coil also includes a second winding 26 for carrying currentto re-set the magnetic field associated with the electromagnetic core.Both the first winding 24 and the second winding 26 are wound about theelectromagnetic core 22. The first winding 24 and the second winding 26are bifilar wound together about the electromagnetic core 22. As will bedescribed, the motor M1 also includes a swinging armature for providingmovement in response to energizing the magnetic field about theelectromagnetic core 22.

The circuit 10 also includes at least one storage capacitor C1 inelectrical communication with the second winding 26. When the magneticfield collapses, the storage capacitor C1 stores residual electricalenergy from the electromagnetic core. The storage capacitor C1 alsofilters a rectified signal from a diode rectification bridge 28 (i.e.,diodes D1-D4) that rectifies the 120VAC input signal from the powersource 11. The electrical switching device Q3 is also in electricalcommunication with the storage capacitor C1 such that, when it is biasedon, the storage capacitor C1 releases the electrical energy storedtherein from the second winding 26. In addition, when the electricalswitching device Q3 is biased on, electric current flows through anelectrical steering device such as a steering diode D6 electricallyconnected thereto. The steering diode 36 provides an electrical path formagnetic energy to be removed from the electromagnetic core through thesecond winding 26. On the other hand, when the electrical switchingdevice Q3 is biased off, the storage capacitor C1 stores electricalenergy obtained from the second winding 26 when the magnetic fieldcollapses. In a preferred embodiment, the electrical switching device Q3is a MOSFET, and the electrical steering device is a steering diode D6.

In order to prevent undesirable or excessive heat generation, a coolingdevice, such as a fan F1, can also be added to the circuit 10. To powerthe cooling device, a winding can be added to generate an appropriatevoltage level. During normal operation, that is, within a typicalfrequency range of about 25 HZ to about 150 HZ, if the frequency isadjusted above a certain level (e.g., above 150 HZ), then when thewinding temperature exceeds 125° Celsius, the frequency can beautomatically reduced to a pre-determined certain level. If thetemperature of coil or winding reaches a second level (e.g., 140°Celsius), the frequency can be reduced even further, for example, to 80HZ. Should the temperature continue to climb and reach a maximum allowedtemperature (e.g., 155° Celsius, the unit can be configured toautomatically shut off until that temperature falls below apredetermined temperature, or until the power device is turned off. Thecoil can also be driven unipolar with pulsating DC power. The powerwinding 1-3 can be wound bifilar with reset winding 2-4.

As described, the stored magnetic energy in the electromagnet is largelyconserved and returned to the storage capacitor C1 at the end of eachduty cycle, whereby it can then be re-used. This increases electricalefficiency. This is possible because two bifilar windings (for optimalmagnetic coupling) are used instead of only one winding. The firstwinding 24 is the power winding for the electromagnet. The secondwinding 26, which in one preferred embodiment is smaller incurrent-carrying capacity than the first winding, is connectedelectrically and in anti-parallel. It functions as a re-set winding.This second winding 26, combined with the steering diode D6, allows apath for the energy to be removed from the magnetic core, which isnecessary before the next power cycle is applied. Since a square wavevoltage is applied to the electromagnet, the armature can close moreswiftly. Thus, this second winding 26 decreases the magnetic field morerapidly and allows the armature to move to its open position morequickly. The net result is that this allows higher frequency operationand greater output volume for a given power device.

As further exemplary, representative, and non-limiting examples,component types are set forth below for the electrical circuit 10 ofFIG. 1. They are only provided to convey an understanding of theinvention, and they are not intended to restrict the scope of theinvention in any way. Nevertheless, preferred components of the circuit10 can be as follows, as available from any suitable vendor:

D1-D4 1N5408 D5 1N4004 D6 MUR850 D7-D10 1N4001 Z1 1N4742 Q1 2N4401 Q22N4403 Q3 IRFP460P IC1-IC2 1CM7555 F1 RS 273-239 SW1 M1

Referring now to FIG. 2, a power device is shown, as readily suited forthe inventive arrangements as described hereinout. More specifically,the representative power device is a spray gun 100, although numerousother power devices are also hereby contemplated. In any event, therepresentative spray gun 100 includes a gun casing 102 and handgrip 104depending therefrom, with a representative on/off trigger switch 106provided therein the grip 104. A reservoir 108 for the medium to besprayed (e.g., paint or other) is secured to the underside of the guncasing 102. This medium to be sprayed is drawn up by a representativepump 110, which is driven by a coil/oscillating armature combination anddisposed within the gun casing 102. Thereafter, this medium to besprayed is conveyed to a representative spray nozzle 112 forapplication. Internally, an electric swinging armature drive 114 ismounted within the gun casing 102 to drive the pump 110. An electroniccontrol circuit 116 for the pump 110 and swinging armature drive 114 isalso disposed within the gun casing 102, although relative positionsthereof are only depicted for exemplary, representative, andnon-limiting purposes. Other suitable arrangements thereof are alsocontemplated hereby. In any event, the electronic control circuit 116for the swinging armature drive 114 preferably comprises the electricalcircuit of FIG. 1, as described hereinout.

Referring again to FIG. 1, when the switch SW1 triggers the currentpulse from the timing circuitry 14, the armature of the motor M1operates at the desired current pulse output pulse width. An exemplarywinding structure for winding 1-3 is 380 turns of 3 X #25AWG wire andwinding 2-4 is 380 turns of 1 X #25AWG wire.

In a preferred embodiment, the electrical circuit 10 is used as part ofa power device. As such, the power device can also include theafore-described power source 12; timing circuitry 14 powered by thepower source 12 for producing a current pulse output having a pulsewidth; a switch Q3 for triggering the current pulse output produced bythe timing circuitry 14; and an armature motor M1 powered by the powersource 12 and in electrical communication with the timing circuitry 14for receiving the current pulse therefrom.

The power device can also comprise a frequency adjustment controlmechanism in electrical communication with the timing circuitry 14 forelectronically varying the pulse width by adjusting the frequencyadjustment control mechanism. In one embodiment, the frequencyadjustment control mechanism can be a potentiometer. In one embodiment,the power device of the pulse width can be about 2.8 ms. In oneembodiment, the current pulse output is a continuous symmetrical output.In one embodiment, the frequency adjustment control mechanism permitsinfinite frequency adjustment within a desired operating frequencyrange.

In another preferred embodiment, a variable speed swinging armaturemotor can comprise an electromagnetic core; a first winding for carryingelectric current to energize a magnetic field about the electromagneticcore; a second winding for carrying current to re-set the magnetic fieldassociated with the electromagnetic core, the first and second windingswound about the electromagnetic core; and a swinging armature forproviding movement in response to the energizing of the magnetic fieldassociated with the electromagnetic core. The first winding and thesecond winding are bifilar wound together about the electromagneticcore. The removal of energy from the electromagnetic core can occurprior to a succeeding tenderization cycle of the electro-magnetic core.The second winding can have a current-carrying capacity that is lessthan a current-carrying capacity of the first winding. The motor canutilize an AC line frequency. In one embodiment, a square wave voltageis applied to the first winding and the second winding. The AC linefrequency can be about 50-60 Hz.

In another embodiment, disclosed herein is a variable frequency driverand swinging armature motor combination. The combination comprises: avariable speed swinging armature motor as previously described and acontrol circuit for controlling the variable speed swinging armaturemotor. The control circuit comprises: timing circuitry for producing acurrent pulse output having a pulse width; a switch for triggering thecurrent pulse output produced by the timing circuitry; a storagecapacitor in electrical communication with the second winding andwherein the storage capacitor stores residual electrical energycollected from when the magnetic field associated with theelectromagnetic core collapses; and an electrical switching device inelectrical communication with the storage capacitor such that, when theelectrical switching device is biased so as to be turned on, the storagecapacitor releases the electrical energy stored therein from the secondwinding.

In one embodiment, the combination further comprises a frequencyadjustment control mechanism in electrical communication with the timingcircuitry for electronically varying the pulse width by adjustment ofthe frequency adjustment control mechanism.

It should be understood that this specification describes exemplary,representative, and non-limiting embodiments of the invention.Accordingly, the spirit and scope of this invention are not limited toany of these embodiments. Rather, the details and features of theseembodiments were disclosed as required. Thus, many changes andmodifications—as apparent to those skilled in the art—are within thescope of the invention without departing from the spirit hereof, and theinventive arrangements are inclusive thereof. Accordingly, to apprisethe public of the spirit and scope of this invention, the followingclaims are made.

1. A power device, comprising: a power source; timing circuitry poweredby said power source for producing a current pulse output having a pulsewidth; a switch for triggering said current pulse output from saidtiming circuitry; and an armature motor powered by said power source andin electrical communication with said timing circuitry for receivingsaid current pulse from said timing circuitry, said armature motorcomprising: an electromagnetic core; a first winding for carryingelectrical current to energize a magnetic field associated with saidelectromagnetic core; a second winding for carrying electrical currentto re-set said magnetic field associated with said electromagnetic core;and a swinging armature for providing movement in response to energizingsaid magnetic field associated with said electromagnetic core, whereinwhen said switch triggers said current pulse from said timing circuitry,said armature operates at said current pulse output pulse width.
 2. Thepower device of claim 1, further comprising: at least one storagecapacitor in electrical communication with said second winding, whereinsaid storage capacitor stores residual electrical energy from saidelectromagnetic core when said magnetic field collapses.
 3. The powerdevice of claim 2, further comprising: an electrical switching device inelectrical communication with said storage capacitor, wherein when saidelectrical switching device is biased on, said storage capacitorreleases electrical energy stored within said second winding.
 4. Thepower device of claim 3, wherein when said electrical switching deviceis biased on, electrical current flows through a steering diode.
 5. Thepower device of claim 3, wherein when said electrical switching deviceis biased off, said storage capacitor stores electrical energy from saidsecond winding.
 6. The power device of claim 3, wherein said electricalswitching device is a MOSFET.
 7. The power device of claim 1, whereinsaid power device is a paint sprayer.
 8. The power device of claim 1,further comprising a frequency adjustment control mechanism inelectrical communication with said timing circuitry for electronicallyvarying said pulse width.
 9. The power device of claim 8, wherein saidfrequency adjustment control mechanism is a potentiometer.
 10. The powerdevice of claim 8, wherein said frequency adjustment control mechanismpermits infinite frequency adjustment within a desired operatingfrequency range.
 11. The power device of claim 1, wherein said pulsewidth is about 2.8 ms.
 12. The power device of claim 1, wherein saidcurrent pulse output is a continuous symmetrical output.
 13. The powerdevice of claim 1, further comprising: an electrical steering deviceelectrically connected to said second winding to provide an electricalpath for magnetic energy to be removed from said electromagnetic corethrough said second winding.
 14. A variable speed swinging armaturemotor, comprising: an electromagnetic core; a first winding for carryingelectrical current to energize a magnetic field associated with saidelectromagnetic core; a second winding for carrying electrical currentto re-set said magnetic field associated with said electromagnetic core,said first winding and said second winding wound about saidelectromagnetic core; and a swinging armature for providing movement inresponse to energizing said magnetic field associated with saidelectromagnetic core.
 15. The variable speed swinging armature motor ofclaim 14, wherein removing energy from said electromagnetic core occursbefore a succeeding energization cycle of said electromagnetic core. 16.The variable speed swinging armature motor of claim 14, wherein saidsecond winding has a current carrying capacity that is less than acurrent carrying capacity of said first winding.
 17. The variable speedswinging armature motor of claim 14, wherein said motor utilizes an ACline frequency.
 18. The variable speed swinging armature motor of claim17, wherein said AC line frequency is about 50-60 Hz.
 19. The variablespeed swinging armature motor of claim 14, wherein a square wave voltageis applied to said first winding and to said second winding.
 20. Avariable frequency driver and swinging armature motor combination,comprising: i) a variable speed swinging armature motor, comprising: anelectromagnetic core; a first winding for carrying electrical current toenergize a magnetic field associated with said electromagnetic core; asecond winding for carrying electrical current to re-set said magneticfield associated with said electromagnetic core, said first winding andsaid second winding wound about said electromagnetic core; and aswinging armature for providing movement in response to energizing saidmagnetic field associated with said electromagnetic core; ii) a controlcircuit for controlling said variable speed swinging armature motor,comprising: timing circuitry for producing a current pulse output havinga pulse width; a switch for triggering said current pulse output fromsaid timing circuitry; at least one storage capacitor in electricalcommunication with said second winding, wherein said storage capacitorstores residual electrical energy from said electromagnetic core whensaid magnetic field collapses; and iii) an electrical switching devicein electrical communication with said storage capacitor, wherein whensaid electrical switching device is biased on, said storage capacitorreleases electrical energy stored within said second winding.
 21. Thecombination of claim 20, further comprising: a frequency adjustmentcontrol mechanism in electrical communication with said timing circuitryfor electronically varying said pulse width.
 22. A power device,comprising: a power source; timing circuitry powered by said powersource for producing a current pulse output having a pulse width; aswitch for triggering said current pulse output from said timingcircuitry; and an armature motor powered by said power source and inelectrical communication with said timing circuitry for receiving saidcurrent pulse from said timing circuitry, said armature motorcomprising: an electromagnetic core; a first winding for carryingelectrical current to energize a magnetic field associated with saidelectromagnetic core; a second winding for carrying electrical currentto re-set said magnetic field associated with said electromagnetic core,said first winding and said second winding wound about saidelectromagnetic core; and a swinging armature for providing movement inresponse to energizing said magnetic field associated with saidelectromagnetic core.
 23. The power device of claim 22 wherein when saidswitch triggers said current pulse from said timing circuitry, saidarmature operates at said current pulse output pulse width.